JPH05264357A - Device for correcting sensitivity of infrared image pickup device - Google Patents

Abstract

PURPOSE:To obtain a device for correcting the sensitivity of infrared image pickup devices which can easily acquire offset correcting data. CONSTITUTION:An infrared image pickup section is provided with a frame decimation circuit 22 which decimates the frame of a detecting signal from an infrared detecting section, frame integration circuit 23 which integrates frames decimated by means of the circuit 22, offset correcting data storing memory 24 which stores the data added by means of the circuit 23 as offset correcting data, and sensitivity correction circuit 21 which corrects the fluctuation of the sensitivity of each infrared detecting element contained in the detecting signal based on the offset correcting data. The offset correcting data are acquired by decimating and integrating a plurality of frame data obtained by scanning a visual field with infrared detectors by moving the detectors to make round in a visual field.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION This invention relates to infrared imaging devices, and more particularly to
The present invention relates to a sensitivity correction device that corrects variations in sensitivity of infrared detection elements in an infrared imaging device using a multi-element infrared detector as infrared detection means. 2. Description of the Related Art In recent years, infrared imaging devices have become more sophisticated and are used in various fields such as cameras and medical equipment. With the spread thereof, there has been a demand for simplification and automation of operation and adjustment of the device. On the other hand, this improvement in performance depends on how effectively the variation of each infrared detecting element formed of a CCD element is suppressed. That is, the greater this variation is, the more uneven the brightness of the image, the more noise is generated.

Generally, in order to correct the variation, there are gain correction and offset correction, but in the present invention, the offset correction data used in the sensitivity correction means of each infrared detection element in the offset correction is used to drive the scanning means of the infrared detection section. By doing so, highly accurate offset correction data is acquired.

[0003]

2. Description of the Related Art Conventionally, offset correction data for sensitivity correction of a multi-element infrared detector is used when a infrared image pickup device is used, and a hot plate having a uniform temperature between an infrared optical path and an optical system of the infrared image pickup device. Insert or insert a background with a nearly uniform temperature, and obtain uniform heat from these. That is, a uniform input is applied to all infrared detecting elements from such a heating plate, and an output signal depending on the sensitivity of each infrared detecting element is taken into a storage means inside the apparatus, and when actually used, it is taken into this storage means. The generated output signal is used as offset correction data.

[0004]

When acquiring offset correction data by the above-mentioned conventional method, it is troublesome for the user of the apparatus to prepare a uniform temperature heating plate each time, and it is also difficult to obtain a uniform temperature hot plate. It is often troublesome to secure the background. Therefore, an object of the present invention is to provide a sensitivity correction device of an infrared imaging device that can easily acquire data for correcting sensitivity variations of each infrared detection element.

[0005]

According to the present invention, an infrared detector 1 having a multi-element infrared detector 11 composed of a plurality of infrared detectors, and an offset correction of each element receiving a detection signal of the infrared detector. In the infrared image pickup device including the infrared image pickup unit 2 for displaying the corrected image on the screen, the infrared image pickup unit is thinned by the frame thinning circuit 22 for thinning the frames of the detection signal from the infrared detection unit and the frame thinning circuit. Based on the offset correction data, a frame integration circuit 23 that integrates the frame, an offset correction data storage memory 24 that stores the data added by the frame integration circuit as offset correction data,
A sensitivity correction circuit 21 that corrects variations in the sensitivity of the infrared detection elements included in the detection signal is provided, and a plurality of frame data obtained by scanning the infrared detector so as to make one round with respect to the visual field is thinned and integrated. It is characterized in that the offset correction data is obtained by performing.

The infrared detector has a gimbal mechanism, and the gimbal mechanism gimbals the multi-element infrared detector so as to go around the visual field.

[0007]

According to the present invention, when the sensitivity variation of each infrared detecting element is corrected, the scanning means of the infrared detecting section is used to detect infrared rays with respect to the object without using a uniform heating plate as in the prior art. A large number of data are collected by scanning the field of view of the unit so as to make one round, and the data is thinned and integrated to obtain offset correction data. Therefore, the more collected data, the more uniform the data, and the same effect as if the uniform hot plate is arranged.

By the way, some infrared image pickup devices employ a gimbal mechanism as a scanning means of the infrared detector in order to enlarge the field of view. The gimbal mechanism is a mechanism used in a gyroscope or the like, and is a mechanism that enables movement in the left-right direction, the vertical direction, the circumferential direction, and the like. Therefore, by controlling the direction of the infrared detector using the gimbal mechanism, it is possible to obtain temperature information from a very wide field of view of the background that is actually the subject to be photographed. Therefore, all the obtained information should be averaged. Thus, the average amount of light can be easily obtained without using a separate heating plate or the like as in the related art, and the offset correction data can be obtained.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 is a block diagram of an embodiment of an infrared imaging device of the present invention. In the figure, 1 is an infrared detection unit, 2 is an infrared imaging unit, and 3 is a monitor television. The infrared detector 1 includes a multi-element infrared detector 11 and a gimbal mechanism 12 that operates the multi-element infrared detector 11 in the left-right direction, the vertical direction, the circumferential direction, and the like.

The infrared image pickup section 2 includes a sensitivity correction circuit 21 and
A frame thinning circuit 22, a frame integrating circuit 23,
An offset correction data memory 24, a switch control circuit 25, a screen display circuit 27, and a scanning control circuit 28 are provided. Further, 26 is an offset acquisition switch on the operation panel, and 221 is an address counter included in the frame thinning circuit 22.

FIG. 2 is an explanatory diagram of the scanning pattern of the infrared detector by the gimbal mechanism. In the figure, 100 is the entire field of view of the infrared imaging device by scanning with the gimbal mechanism. The center position O is the center of the entire visual field, that is, the center of the initial optical axis.
P is the center position when the infrared sensor 11 is swung from the center position O to the right by, for example, an angle of 10 degrees, and the shaded portion 101 is the effective field of view of the infrared sensor 11. Then, in the present invention, in order to obtain the offset correction data, the infrared detector is rotated in the direction of the arrow with a radius of gyration of 10 degrees to scan the field of view by utilizing the gimbal mechanism. Note that the infrared detector 11 is not limited to a circular scan, but may be a polygon such as a quadrangle as long as the same screen is not scanned.

Then, the gimbal scanning of the infrared detector 11 is performed by the scanning control circuit 28 in the infrared imaging section 2 in accordance with a preset scanning pattern. 1 and 2, the basic sequence for acquiring offset correction data is as follows. That is, first, the offset acquisition switch 26 is turned on and the gimbal scanning of the infrared detector 11 is started according to the scanning pattern shown in FIG. Image data obtained in synchronization with gimbal scanning is subjected to constant thinning by the frame thinning circuit 22, and then frame integration circuit 23 performs frame integration on a predetermined frame. At this time, the frame capture time is determined according to the frame rate of the infrared imaging device. Then, the frame-integrated data for each element of the infrared detecting element is stored in the offset correction data memory 24, and thereafter, this stored data is used as the offset correction data.

FIG. 3 is a detailed circuit diagram of the infrared imaging section of FIG. As shown in the figure, the sensitivity correction circuit 21 includes an arithmetic unit (AL
U) 211, selector 212, and memory (ROM) 2
13, a subtractor 214, and a selector 215. The frame thinning circuit 22 includes a gate circuit 222 and an address counter 221. The frame integration circuit 23 includes an adder 231 and a subtractor 232. Further, the screen display circuit 27 includes a screen display memory 271, an address counter 272, and a D / A converter 273. The numbers 12, 14, and 24 on each line are the number of transfer bits. Further, FSC is a frame synchronization clock and IMC is a pixel clock. These clocks are used as the address counter 221 of the frame thinning circuit 22.
Is input to the address counter 272 of the screen display circuit 27.

By the way, when the user turns on the offset acquisition switch 26 on the operation panel, this signal is input to the scanning control circuit 28 and the switch control circuit 25, and the infrared detecting section 1 in FIG. The gimbal scanning shown in is started. The activation signal from the switch control circuit 25 is input to the address counter 221, which is synchronized with the frame synchronization clock FSC from a clock source (not shown) to generate the pixel clock IM.
Start counting C. The pixel clock IMC is a clock that sequentially excites each infrared detection element. By this pixel clock IMC, analog data is input to the A / D converter 13 from each infrared CCD element, and the IMC is simultaneously input to the address counter 221. It is assumed that the multi-element infrared detecting element is composed of N _X elements in the X direction and N _Y elements in the Y direction.

Normally, when frame thinning is not performed,
A count signal is sent to the offset correction data memory 24, and the offset correction data memory 24 fetches N _X × N _Y offset correction data. When the frame skipping in the frame thinning-out circuit 22 monitors at the N _X × N _Y number of count address counter 221, for example, and performs integration once for every two frames, the first N _X × N _Y pieces The data is taken into the frame integration circuit 23 during the period of (2), and the gate circuit 222 does not take the data into the integration circuit 23 during the next period of N _X × N _Y.

In the frame integration circuit 23, the adder 231
Thus, the frame data from the gate circuit 222 and the data from the subtractor 232 are added and loaded into the offset correction data memory 24. The subtracter 232 subtracts the upper 12 bits of the data from the same offset correction data memory 24 from the 24 bits of data from the offset correction data memory 24 and returns it to the adder 231. The addition data of the adder 231 is the subtractor 2 in the sensitivity correction circuit 21.
14 is input.

In the sensitivity correction circuit 21, the arithmetic unit 211 is A
The digital value from the / D converter 13 is input to one side, and the data of the selector 212 is input to the other side to perform subtraction. In this case, linear interpolation correction data for correcting each element is stored in advance in the table of the memory 213, and the selector 212 is based on the input data from the A / D converter 13 and is a table adapted to the input data. The content of is read and input to the arithmetic unit 211. The subtractor 214 is the calculator 211
Linear interpolation corrected calculation data and frame integration circuit 2
Subtraction with the addition data of the adder 231 in 3
If the calculation result has overflowed, it is stored in the screen display memory 271 via the selector 215 which outputs.

In the screen display circuit 27, the address counter 221 for inputting the frame synchronization clock FSC and the pixel clock IMC causes the above-mentioned address counter 221.
Similarly, for example, when N _X is counted, a count signal is transmitted to read the display data from the screen display memory 271 and display it on the monitor television after D / A conversion. By the way, in this embodiment, frame integration for a maximum of 4096 frames is performed. In this case, the maximum number can be changed in 2 ^N frames. Here, frame thinning is performed by changing the sampling time of integration (frame addition).

The frame rate of this infrared imaging device is A
(Hz), the capture time per frame is 1 / A second, and assuming that a maximum of 4096 frames is captured, it has a time constant of 4096 / A second, and temporal frame thinning is performed (the thinning time is variable. ), For example, once every two frames or once every four frames, the effects of integration can be changed and used.

The frame integration circuit 23 receives the latest frame data sequentially input and the offset correction data memory 2
The past frame data stored in No. 4 is sequentially added for each infrared detection element to obtain offset correction data for each element. For sensitivity correction as a whole, in the sensitivity correction circuit 21, the arithmetic unit (ALU) 211 performs addition / subtraction based on the offset correction data for each element, basic sensitivity correction is performed, and the subtractor 214 is used in the previous stage. Subtract the obtained offset correction data to perform more precise correction.

[0021]

As described above, according to the present invention,
There is an effect that the user can easily obtain the offset correction data for correcting the sensitivity variation of each infrared detecting element without using a uniform heating plate as in the conventional case.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of an infrared imaging device of the present invention.

FIG. 2 is an explanatory diagram of a scanning pattern of an infrared detector using a gimbal mechanism.

FIG. 3 is a detailed circuit diagram of the infrared imaging unit in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Infrared detection part 2 ... Infrared imaging part 3 ... Monitor television 11 ... Multi-element type infrared detector 12 ... Gimbal mechanism 13 ... A / D converter 21 ... Sensitivity correction circuit 22 ... Frame thinning circuit 23 ... Frame integration circuit 24 ... Offset correction data memory 25 ... Switch control circuit 26 ... Offset acquisition switch 27 ... Screen display circuit 28 ... Scanning control circuit 211 ... Calculators 214,232 ... Subtractor 221,272 ... Address counter 222 ... Gate 231 ... Adder

Claims (2)

[Claims] 1. An infrared detecting section (1) having a multi-element infrared detector (11) comprising a plurality of infrared detecting elements.
And an infrared imaging unit (2) that receives a detection signal of the infrared detection unit and performs offset correction of each element to display a corrected image on the screen, the infrared imaging unit comprising: A frame thinning circuit (22) for thinning out the frames of the detection signal, a frame integrating circuit (23) for integrating the frames thinned by the frame thinning circuit, and the data added by the frame integrating circuit as offset correction data. An infrared correction data storage memory (24) for storing and a sensitivity correction circuit (21) for correcting variations in the sensitivity of the infrared detection elements included in the detection signal based on the offset correction data are provided. Decimation and integration of a plurality of frame data obtained by scanning the vessel around the field of view Sensitivity correction device of the infrared imaging apparatus is characterized in that so as to obtain more offset correction data. 2. The infrared detector comprises a gimbal mechanism,
The sensitivity correction device for an infrared imaging device according to claim 1, wherein the multi-element infrared detector is scanned by the gimbal mechanism so as to scan the visual field once.